Biology subjects

Fuchs, N.

Publications and source records attributed to Fuchs, N..

8 recordsLinked to original sources

bioRxiv2026

Phage Display-Derived Cyclic Peptides Target TREM2 and Modulate Microglial Responses under Amyloid Stress

Triggering receptor expressed on myeloid cells 2 (TREM2) is a key regulator of microglial function and a promising therapeutic target in Alzheimers disease. While current strategies have largely focused on antibody-based agonists, alternative modalities capable of modulating TREM2 signaling remain underexplored. Here, we report the discovery of TREM2-binding cyclic peptides using a disulfide-constrained phage display library. Screening and biophysical validation identified multiple binders, with TREM2-6 and TREM2-12 exhibiting micromolar affinity. Both peptides modulated microglial responses in human iPSC-derived model of amyloid stress and in neuron-microglia co-cultures. Molecular dynamics simulations supported stable peptide-TREM2 interactions, with TREM2-12 displaying a more constrained binding mode. In vitro pharmacokinetic profiling revealed favorable plasma and intestinal stability but limited permeability, consistent with cyclic peptide scaffolds. Together, these findings establish cyclic peptides as a viable modality for targeting TREM2 and provide a foundation for the development of tunable neuroimmune therapeutics. Insert Table of Contents artwork here O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/720287v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@fbe978org.highwire.dtl.DTLVardef@9cd946org.highwire.dtl.DTLVardef@17cb644org.highwire.dtl.DTLVardef@a2669e_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2025

HTS-Oracle: Experimentally validated AI-enabled prioritization for generalizable small molecule hit discovery

High-throughput screening (HTS) remains a central pillar of small molecule discovery yet routinely fails for immune receptors and protein-protein interaction-driven targets. Here, we introduce HTS-Oracle, an experimentally validated AI system for prospective hit discovery that integrates molecular language modeling with cheminformatics to prioritize bioactive compounds at scale. We deploy HTS-Oracle across three clinically validated yet historically intractable immune targets, TREM2, CHI3L1, and CD28, representing cryptic binding pockets, intrinsically disordered proteins, and protein-protein interaction-driven immune checkpoint, respectively. Across the tested targets, HTS-Oracle reduces experimental screening requirements by up to >99% while increasing hit rates by up to 176-fold relative to traditional HTS. Notably, the platform remains predictive under extreme data sparsity, achieving an eightfold improvement for CD28 despite fewer than 2% actives in training. By consistently enriching for experimentally validated hits, HTS-Oracle establishes a new performance benchmark for hit discovery and unlocks small molecule access to immune targets long regarded as chemically inaccessible.

bioinformatics↗

bioRxiv2025

High-Throughput Fragment Screening Identifies a New Small Molecule Scaffold that Modulates TREM2 Signaling

Fragment-based drug discovery (FBDD) remains a powerful tool in drug development for targeting a wide range of proteins and identifying new small molecule-based scaffolds. Here, we explored a fragment library of 3,200 compounds using a temperature-related intensity change (TRIC)-based high-throughput screening (HTS) approach, and successfully identified new scaffolds that bind to triggering receptor expressed on myeloid cells 2 (TREM2), a relevant target in neurodegenerative diseases and cancer immunotherapy. We first validated the hits with dose-dependent assays, then chose the three most promising compounds (2M06, 6B10, 7G19) with binding affinities in the low to medium micromolar range for a "SAR by catalog" study. We screened 29 selected derivatives and subsequently evaluated them with dose-dependent experiments, a thermal shift assay (TSA), selectivity studies with off-targets (LAG-3, TREM1), and finally, in vitro TREM2 activation assays. In this SAR study, derivative 6B10-9 emerged as the lead compound with moderate TREM2 binding affinity (KD = 68.3 {micro}M) and significant effects on TREM2-dependent phosphorylation of SYK and DAP12 in HEK cells as wells as on microglial phagocytosis in HMC3 cells. Additionally, an in silico analysis revealed that 6B10-9 forms a stable complex with TREM2 via hydrogen bonding, which maintains its structural integrity during extended molecular dynamics (MD) simulations. These results suggest that 6B10-9 could serve as a promising lead for future optimizations in the development of small molecule-based TREM2 modulators.

pharmacology and toxicology↗

bioRxiv2025

TREM2 Hit Discovery Using TRIC Technology: A Proof-of-Concept High-Throughput Screening Approach

Triggering receptor expressed on myeloid cells 2 (TREM2) is an immunomodulatory receptor implicated in both neurodegenerative diseases and cancer. Depending on the context, TREM2 agonists or inhibitors hold therapeutic potential. To date, the majority of TREM2-targeted strategies have centered on monoclonal antibodies (mAbs), which face limitations such as poor tissue penetration and potential immunogenic side effects. To overcome these challenges and expand the chemical space for TREM2-targeting agents, we developed a high-throughput screening (HTS) platform to identify novel small molecule TREM2 binders. Using temperature-related intensity change (TRIC) technology in a 384-well plate format (NanoTemper Dianthus), we screened two focused compound libraries comprising over 1,200 molecules. From this screen, 18 preliminary hits (1.44% hit rate) were identified and subsequently validated by dose-response binding studies using microscale thermophoresis (MST), yielding four validated hits (0.32% hit rate) with binding affinities in the high to medium micromolar range (e.g., T2337, KD = 22.4 M). The binding of the top hit, T2337, was further validated using surface plasmon resonance (SPR). Additionally, we assessed the functional activity of all four validated hits in a cellular assay measuring TREM2-mediated Syk phosphorylation in HEK293 cells co-expressing human TREM2 and its adaptor protein DAP12. These findings establish a robust and scalable platform for the discovery of small molecule TREM2 modulators and serve as a proof-of-concept for broader HTS campaigns targeting TREM2.

pharmacology and toxicology↗

bioRxiv2025

Immune surveillance and pruning of neuronal stem cells in the medaka retina

Stem cell populations in tissues require precise regulation of their number and quality to maintain proper organ growth. Amongst various regulatory mechanisms, immune cells are emerging to directly regulate stem cell populations. The medaka retinal stem cell (RSC) niche, a model for lifelong neurogenic growth, provides a system to study immune-stem cell interactions. We investigate how microglia, resident macrophages of the central nervous system, regulate the RSC niche. We identify that bona fide RSCs express the chemokine Ccl25b while its cognate receptor, Ccr9a, is expressed in microglia. These microglia form a surveillance ring adjacent to the RSC niche and actively phagocytose RSCs. Interference with microglia by deletion of spi1b reveals that microglia absence leads to increased numbers of ccl25b-positive RSCs and results in morphological defects of the retina. Targeted mutation of ccl25b specifically affects microglia mobility under injury conditions, however, we did not observe any morphological defects indicating that Ccl25b-Ccr9a signaling is not essential for stem cell maintenance. Overall, our data show that under homeostatic conditions the individual RSCs, essential for proper eye development, are actively phagocytosed by immune surveillance.

developmental biology↗

bioRxiv2024

From Virtual Screens to Cellular Target Engagement: New Small Molecule Ligands for the Immune Checkpoint LAG-3

Herein, we performed a virtual screening study to discover new scaffolds for small molecule-based ligands of the immune checkpoint lymphocyte-activation gene 3 (LAG-3). Molecular dynamics (MD) simulations using the LAG-3 structure revealed two putative binding sites for small molecules: the antibody interface and a lipophilic canyon. A 3D pharmacophore screening resulted in the identification of potential ligands for these binding sites and afforded a library of 25 compounds. We then evaluated the screening hits for LAG-3 binding via microscale thermophoresis (MST) and surface plasmon resonance (SPR). Our biophysical screening identified two binders with KD values in the low micromolar range, compounds 3 (antibody interface) and 25 (lipophilic canyon). Furthermore, we investigated the ability of LAG-3 hits to en-gage LAG-3 on a cellular level using a cellular thermal shift assay (CETSA), where compound 3 emerged as a promising candidate for future development.

pharmacology and toxicology↗

bioRxiv2024

Direct single-molecule detection and super-resolution imaging with a low-cost portable smartphone-based microscope

We present a novel, low-cost, portable smartphone-based fluorescence microscope capable of directly detecting single molecules without signal amplification. The setup leverages the image sensors and data handling capacity of mass-produced smartphones, making it adaptable to any smartphone and capable of detecting single molecules across the visible spectral range. We showcase this capability through single-molecule measurements on DNA origami models and super-resolution microscopy of biological cells by single-molecule localization microscopy. This development paves the way for biotechnology innovations making use of massively distributed or personalized assays with single-molecule sensitivity with the potential to revolutionize digital bioassays, point-of-care diagnostics, field expeditions, STEM outreach, and life science education.

biophysics↗

bioRxiv2021

Identification, Characterization and Synthesis of Natural Parasitic Cysteine Protease Inhibitors -- More Potent Falcitidin Analogs

Protease inhibitors represent a promising therapeutic option for the treatment of parasitic diseases such as malaria and human African trypanosomiasis. Falcitidin was the first member of a new class of inhibitors of falcipain-2, a cysteine protease of the malaria parasite Plasmodium falciparum. Using a metabolomics dataset of 25 Chitinophaga strains for molecular networking enabled identification of over 30 natural analogs of falcitidin. Based on MS/MS spectra, they vary in their amino acid chain length, sequence, acyl residue, and C-terminal functionalization; therefore, they were grouped into the four falcitidin peptide families A-D. The isolation, characterization and absolute structure elucidation of two falcitidin-related pentapeptide aldehyde analogs by extensive MS/MS spectrometry and NMR spectroscopy in combination with advanced Marfeys analysis was in agreement with the in silico analysis of the corresponding biosynthetic gene cluster. Total synthesis of chosen pentapeptide analogs followed by in vitro testing against a panel of proteases revealed selective parasitic cysteine protease inhibition and additionally low-micromolar inhibition of -chymotrypsin. The pentapeptides investigated here showed superior inhibitory activity compared to falcitidin.

microbiology↗